instead of royalty free shitty music you could just get an open source free music software and compose anything for the precise need you have and it will be less work then finding something decent that still isnt yours even if its legal
how will you know the site to get free music are safe then and if that music is free afterall...it just might. Do you have an idea of what kind of traditional and pop japanese music? Instrumental? particular style or vibe , length ,....etc Maybe if you precise a little I could suggest
Royalty-free just means you don't pay a fee everytime the music is played. For example if a bar/pub owner has bands performing or a radio with music on he or she must pay royalties to the artists.
Even if music is royalty free you still need to pay the licensing fee or ask permission. Another example, I'm a professional composer and one of my fantasy tracks got used for some fantasy books advert. The guy paid the licensing fee to use the music and every time the advert is shown I get a very small royalty fee from it. Sometimes there is no royalty fee, but that doesn't mean the music is 'copyright' free. Although, if it's such a small project or a school project and the person makes no money I don't think anyone would mind. I've let people use my music for free for their school projects before.
You would think the major labels carrying pop music would demand royalties though for every time their music is played. Not all pop music is on a major label, certainly, though it seems really ironic to search for pop music that's on a label that doesn't demand royalties at the same time.
Well yeah, I wouldn't put much hope in finding pop music that is royalty-free either. And you always get what you pay for in terms of quality. For example, the $10 licensing fee orchestra "trailer" music listed in stock music websites sounds absolutely terribly produced and composed compared to stuff for $300 or $2000 at the other end of the Two Steps From Hell kind of movie licensing extreme. But they always do deals. I know the guy that does the Dreamhack (Sweden's biggest computer thing) and they only pay a few hundred euro to use a TSFH song for the entire year.
If the OP were to find a very cheap licensing fee for a J-Pop band I can't imagine the music would sound good in either composition, performance or production. If it's a school project or something I'd say just write for permission or use it anyway. But if you wish to have lots of public views then you can't use stuff illegally without eventually having every view you've gotten demanded in royalties.
You get what you pay for though. These sites that offer low cost licensing music and/or royalty free almost always pale in comparison and usually aren't professional sounding at all. If it's a project you're putting a lot of time into I'd just pay a licensing fee for something decent quality. If it's a very small project and you wouldn't be having Youtube advertising revenue or anything like that then I'd say just use whatever and see if you get asked to remove it or not. If you do you can always change the music at that point and simply re-upload, assuming you don't care for the view counter resetting.